There still may be scratches on the disk diffusing the light. CDs do not go "bad" as magnetic media will, but they may become scratched or scuffed at an inopportune place without being apparent. If the quality of recording is near the threshold of readability, any change to the surface may render it unreadable.
There is the banana trick among other things. Rub a fresh banana onto the CD, clean off with the inside of the banana peel, then wash with soap and water. The wax left behind may fill in scratches and improve readability. Probably any type of wax will work, but if thick wax is used it will have to be buffed down onto the surface. Buffing is creation of heat through friction. http://www.geeksaresexy.net/2007/08/11/how-to-use-a-banana-to-fix-a-scratched-cd-or-dvd/
An older CD player may read the disk. After trying many players in different computers you may find one that plays it.
Another option is to obtain software specially made to read the CD. It will try over and over and over again to read the bad spot until hopefully successful.
Try placing the CD in the freezer then placing in the reader directly from the freezer. Also try warming it a little bit. The hope is to change the dynamic just enough to go back over the threshold of readability.